Future Climate Change and Anthropogenic Disturbance Promote the Invasions of the World's Worst Invasive Insect Pests.

Invasive insect pests adversely impact human welfare and global ecosystems. However, no studies have used a unified scheme to compare the range dynamics of the world's worst invasive insect pests. We investigated the future range shifts of 15 of the world's worst invasive insect pests. Although future range dynamics varied substantially among the 15 worst invasive insect pests, most exhibited large range expansions. Increases in the total habitat suitability occurred in more than ca. 85% of global terrestrial regions. The relative impacts of anthropogenic disturbance and climate variables on the range dynamics depended on the species and spatial scale. Aedes albopictus, Cinara cupressi, and Trogoderma granarium occurred four times in the top five largest potential ranges under four future climate scenarios. Anoplophora glabripennis, Aedes albopictus, and Co. formosanus were predicted to have the largest range expansions. An. glabripennis, Pl. manokwari, Co. formosanus, and So. invicta showed the largest range centroid shifts. More effective strategies will be required to prevent their range expansions. Although the strategies should be species-specific, mitigating anthropogenic disturbances and climate change will be essential to preventing future invasions. This study provides critical and novel insights for developing global strategies to combat the invasions of invasive insect pests in the future.

Future range dynamics of Asian yellow-legged hornets (Vespa velutina) and their range overlap with Western honey bees (Apis mellifera) reveal major challenges for bee conservation in Europe.

BACKGROUND: The invasion of Asian yellow-legged hornets (Vespa velutina) has significantly affected Western honey bees (Apis mellifera) and apiculture in Europe. However, the range dynamics of this hornet and its range overlap with the bees under future change scenarios have not yet been clarified. Using land-use, climate, and topographical datasets, we projected the range dynamics of this hornet and Western honey bees in Europe and the future overlap of their ranges. RESULTS: We found that climatic factors had stronger effects on the potential ranges of the hornets compared with land-use and topographical factors. A considerable range expansion of this hornet was predicted, and an increase in the overlap between this pest and the bees was primarily caused by future decreases in temperature seasonality. Additionally, we detected future range expansions of the hornet in the UK and France; future range overlap between this pest and Western honey bees in the UK, Ireland, Portugal, and France; and future overlap between the ranges of this pest and bees but not under recent conditions was mainly projected in Germany, Denmark, and the UK. CONCLUSION: Mitigating future climate change might effectively control the proliferation of the hornets and their effects on the bees. Strategies for preventing the invasion of this pest and developing European apiculture should be developed and implemented in these regions where future range overlap between them was projected. Given that climate-change scenarios may result in uncertainty in our projections, further investigation is needed to clarify future range changes of our target species. © 2024 Society of Chemical Industry.

Niche and Range Shifts of Aedes aegypti and Ae. albopictus Suggest That the Latecomer Shows a Greater Invasiveness.

The yellow fever (Aedes aegypti) and Asian tiger (Ae. albopictus) mosquitos are major vectors of global mosquito-borne pathogens. However, their niche and range shifts, the underlying mechanisms, and related relative invasion rates remain scarcely known. We examined the niche and range shifts between the native and invasive Ae. aegypti and Ae. albopictus populations through dynamic niche and range models and the largest occurrence record datasets to date. We detected substantial niche and range expansions in both species, probably because the introduced populations have more opportunities to acclimate to diverse environmental conditions than their native counterparts. Mitigating climate change could effectively control their future invasions, given that future climate changes could promote their invasiveness. Additionally, compared to the introduced Ae. aegypti, the more recent invader Ae. albopictus had greater niche and range expansion over its shorter invasion history. In terms of the range shifts, Ae. albopictus had an invasion rate approximately 13.3 times faster than that of Ae. aegypti, making it a more invasive vector of global mosquito-borne pathogens. Therefore, considering its higher invasion rate, much more attention should be paid to Ae. albopictus in devising our strategies against prevailing global mosquito-borne pathogens than Ae. aegypti. Since small niche shifts could result in their large range shifts, niche shifts might be a more important indicator for biological invasion assessments.

Climatic niche and range shifts of grey squirrels (Sciurus carolinensis Gmelin) in Europe: An invasive pest displacing native squirrels.

BACKGROUND: As an invasive pest from North America, grey squirrels (GSs; Sciurus carolinensis Gmelin) are displacing native squirrels in Europe. However, the climatic niche and range dynamics of GSs in Europe remain largely unknown. Through niche and range dynamic models, we investigated climatic niche and range shifts between introduced GSs in Europe and native GSs in North America. RESULTS: GSs in North America can survive in more variable climatic conditions and have much wider climatic niche breadth than do GSs in Europe. Based on climate, the potential range of GSs in Europe included primarily Britain, Ireland, and Italy, whereas the potential range of GSs in North America included vast regions of western and southern Europe. If GSs in Europe could occupy the same climatic niche space and potential range as GSs in North America, they would occupy an area ca. 2.45 times the size of their current range. The unfilling ranges of GSs in Europe relative to those of GSs in North America were primarily in France, Italy, Spain, Croatia, and Portugal. CONCLUSION: Our observations implied that GSs in Europe have significant invasion potential, and that range projections based on their occurrence records in Europe may underestimate their invasion risk. Given that small niche shifts between GSs in Europe and in North America could lead to large range shifts, niche shifts could be a sensitive indicator in invasion risk assessment. The identified unfilling ranges of the GS in Europe should be prioritized in combating GS invasions in the future. © 2023 Society of Chemical Industry.

Niche and Range Shifts of the Fall Webworm (Hyphantria cunea Dury) in Europe Imply Its Huge Invasion Potential in the Future.

The fall webworm (Hyphantria cunea Dury) has a strong impact on agricultural systems in Europe. However, its invasive potential, which was inherited from its native niche in North America, remains unknown. Here, we investigated the climatic niche and range shifts of the fall webworm in Europe and compared them with those in native North America, then assessed the worms' invasive potential in Europe. Compared with the fall webworm in Europe, those in North America survived in more diverse climatic conditions, which was closely associated with their broader niche and larger potential ranges in Europe. If the fall webworm in Europe could exploit the native niche inherited from those in North America to adapt to climatic conditions in Europe, their potential ranges in Europe could be 5.5-fold those based on the niche as introduced in Europe. The potentially unfilled ranges of the fall webworm in Europe were mainly detected in vast regions of Europe, excluding Norway, Sweden, Finland, North Russia, Hungary, Croatia, Romania, and Ukraine, suggesting that, without strict control, these vast regions might be preferably invaded by the fall webworm in Europe in the future. Therefore, strict control against its invasion is needed. Given that small niche shifts in this invasive insect could result in large range shifts, the niche shifts represent a more sensitive indicator of invasion risk than range shifts.

Global niche and range shifts of Batrachochytrium dendrobatidis, a highly virulent amphibian-killing fungus.

Batrachochytrium dendrobatidis (Bd) is one of the world's most invasive species, and is responsible for chytridiomycosis, an emerging infectious disease that has caused huge losses of global amphibian biodiversity. Few studies have investigated invasive Bd's niche and range relative to those of native Bd. In the present study, we applied niche and range dynamic models to investigate global niche and range dynamics between native and invasive Bd. Invasive Bd occupied wider and different niche positions than did native Bd. Additionally, invasive Bd was observed in hotter, colder, wetter, drier, and more labile climatic conditions. Contrast to most relevant studies presuming Bd's niche remaining stable, we found that invasive Bd rejected niche conservatism hypotheses, suggesting its high lability in niche, and huge invasion potential. Bd's niche non-conservatism may result in range lability, and small niche expansions could induce large increases in range. Niche shifts may therefore be a more sensitive indicator of invasion than are range shifts. Our findings indicate that Bd is a high-risk invasive fungus not only due to its high infection and mortality rates, but also due to its high niche and range lability, which enhance its ability to adapt to novel climatic conditions. Therefore, invasive Bd should be a high-priority focus species in strategizing against biological invasions.

Niche and range dynamics of Tasmanian blue gum (Eucalyptus globulus Labill.), a globally cultivated invasive tree.

The ecological niche concept has provided insights into various areas in ecology and biogeography. Although there remains much controversy regarding whether species niches are conserved across space and time, many recent studies have suggested that invasive species conserve their climatic niche between native and introduced ranges; however, whether the climatic niche of cultivated invasive species, whose niches are strongly affected by human activities, are conserved between native and introduced ranges remains unclear. Additionally, the range dynamics of invasive species in their native and introduced regions have not been extensively studied. Here, we investigated the niche and range dynamics of Tasmanian blue gum (Eucalyptus globulus Labill.), a globally cultivated invasive tree, using ecological niche models and niche dynamic analyses. The most important factors affecting the niche changes between native and introduced Tasmanian blue gum were max temperature of the warmest month and precipitation of the wettest month. The climate niche was not conserved between introduced and native range Tasmanian blue gum; moreover, the niche area of the former was ca. 7.4 times larger than that of the latter, as introduced Tasmanian blue gum could survive in hotter, colder, wetter, and drier climates. In addition, the potential range of introduced Tasmanian blue gum was ca. 32 times larger than that of its native counterpart. Human introduction and cultivation may play a key role in the niche and range expansion of introduced Tasmanian blue gum. Given that small increases in niche area can result in large range expansions, the niche expansion of an invasive species could be used to evaluate invasion risk, which might even be more sensitive than range expansions.

Cultivation has selected for a wider niche and large range shifts in maize.

Background: Maize (Zea mays L.) is a staple crop cultivated on a global scale. However, its ability to feed the rapidly growing human population may be impaired by climate change, especially if it has low climatic niche and range lability. One important question requiring clarification is therefore whether maize shows high niche and range lability. Methods: We used the COUE scheme (a unified terminology representing niche centroid shift, overlap, unfilling and expansion) and species distribution models to study the niche and range changes between maize and its wild progenitors using occurrence records of maize, lowland teosinte (Zea mays ssp. parviglumis) and highland teosinte (Zea mays ssp. mexicana), respectively, as well as explore the mechanisms underlying the niche and range changes. Results: In contrast to maize in Mexico, maize did not conserve its niche inherited from lowland and highland teosinte at the global scale. The niche breadth of maize at the global scale was wider than that of its wild progenitors (ca. 5.21 and 3.53 times wider compared with lowland and highland teosinte, respectively). Compared with its wild progenitors, maize at global scale can survive in regions with colder, wetter climatic conditions, as well as with wider ranges of climatic variables (ca. 4.51 and 2.40 times wider compared with lowland and highland teosinte, respectively). The niche changes of maize were largely driven by human introduction and cultivation, which have exposed maize to climatic conditions different from those experienced by its wild progenitors. Small changes in niche breadth had large effects on the magnitude of range shifts; changes in niche breadth thus merit increased attention. Discussion: Our results demonstrate that maize shows wide climatic niche and range lability, and this substantially expanded its realized niche and potential range. Our findings also suggest that niche and range shifts probably triggered by natural and artificial selection in cultivation may enable maize to become a global staple crop to feed the growing population and adapting to changing climatic conditions. Future analyses are needed to determine the limits of the novel conditions that maize can tolerate, especially relative to projected climate change.

Double-edged effects of climate change on plant invasions: Ecological niche modeling global distributions of two invasive alien plants.

The prediction of the potential distribution of invasive alien species is key for the control of their proliferation. This study developed ensemble niche models to explore the distribution patterns of Cecropia peltata and Ulex europaeus under baseline and future conditions, as well as the factors that regulate them. The models were based on occurrence records as well as climate, land-use and topography datasets. Climatic factors played a stronger role than land-use and topographical factors in their distribution patterns. Additionally, temperature seasonality and temperature annual range were the optimal predictor for the global distributions of C. peltata and U. europaeus, respectively. Under the baseline-RCP 8.5 scenario in 2070, significant increases in habitat suitability for C. peltata were generally detected in tropical regions, while for U. europaeus under the same condition, significant increases in habitat suitability were generally observed in west coast of South America and Europe, suggesting the impacts of climate changes on species distribution may be species specific. The contrast changes of suitable habitat areas for U. europaeus under the baseline-2.6 and 8.5 scenarios may suggest that the scenarios of climate changes may modify its distribution patterns and variations in suitable habitats. The double-edged effects of global warming on plant invasions may be a result of the scenario specific climate change and the species-specific responses to changes in climate. Our findings highlight the importance of climate change scenario specific and species-specific research on the impact of climate change on plant invasions.

Land-use change drives present and future distributions of Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

The fall armyworm (Spodoptera frugiperda J.E. Smith) is one of the most notorious pests of several crops in the world. However, to date, few studies have simulated the future distribution patterns of fall armyworm under rapid global changes. Though the relative influences of climate and land-use on species distribution might depend on the spatial scales of the studies, it is not known whether this rule is applicable to pests which mostly feed on crops. Here, we developed MaxEnt models to explore the distribution patterns of fall armyworm, as well as the relative influences of land-use change, topography and climate change on them. Under the present conditions and scenarios of RCP 2.6 and 8.5 (the most optimistic and pessimistic emissions scenarios, respectively), high potential habitats of fall armyworm were mostly recorded along the east coast areas of the USA, the State of Florida, Mexico, Central America, southern part of Brazil, central Africa, and southern Asia. Among all of the continents, Africa will face the greatest increase of the threats from fall armyworm in future. Under RCP 2.6 scenario, both the potential habitats and areas with increased habitat suitability were larger than those under RCP 8.5. Therefore, much more effort is required to control fall armyworm under RCP 2.6 scenario. Compared to climate change, land-use changes are more important in shaping the distribution patterns of fall armyworm. Therefore, the concentration of resources might modify the relative influence of climate and land-use in species distributions at large scales. Thus, regulating land-use might prove effective for mitigating the proliferation of fall armyworm. In general, C4 annual crops and managed pastures provide more suitable habitats for fall armyworm than C3 annual crops. Our findings demonstrate that delineating resource concentrations could provide a new approach towards controlling fall armyworm under current and future global change.

Elevational patterns of the percentages of plant genera with tropical and temperate affinities in Nepal.

BACKGROUND: Geographical patterns of species diversity are one of the key topics in biogeography and ecology. The effects of biogeographical affinities on the elevational patterns of species diversity have attracted much attention recently, but the factors driving elevational patterns of the percentages of plants with tropical and temperate biogeographical affinities have not been adequately explored. METHODS: We first used univariate least squares regressions to evaluate the effects of each predictor on the elevational patterns of the percentages of plant genera with tropical and temperate affinities in Nepal. Then, the lowest corrected Akaike information criterion value was used to find the best-fit models for all possible combinations of the aforementioned predictors. We also conducted partial regression analysis to investigate the relative influences of each predictor in the best-fit model of the percentages of plant genera with tropical and temperate affinities. RESULTS: With the increase of elevation, the percentage of plant genera with tropical affinity significantly decreased, while that of plant genera with temperate affinity increased. The strongest predictor of the percentages of plant genera with tropical affinity in the examined area was the minimum temperature of the coldest month. For the elevational patterns of the percentages of plant genera with temperate affinity, the strongest predictor was the maximum temperature of the warmest month. Compared with mid-domain effects (MDE), climatic factors explained much more of the elevational variation of the percentages of plant genera with tropical and temperate affinities. DISCUSSION: The elevational patterns of the percentages of plant genera with tropical affinities and the factors driving them supported the revision of the freezing-tolerance hypothesis. That is, freezing may filter out plant genera with tropical affinity, resulting in the decrease of their percentages, with winter coldness playing a predominant role. Winter coldness may not only exert filtering effects on plant genera with tropical affinity, but may also regulate the interactions between plant genera with tropical and temperate affinities. The elevational patterns of tropical and temperate plant diversities, and those of their percentages, might be controlled by different factors or mechanisms. Freezing-tolerance and the interactions between plant genera with tropical and temperate affinities regulated by climatic factors played stronger roles than MDE in shaping the elevational patterns of the percentages of plant genera with tropical and temperate affinities in Nepal.

Support for the elevational Rapoport's rule among seed plants in Nepal depends on biogeographical affinities and boundary effects.

As one of the most important hypotheses on biogeographical distribution, Rapoport's rule has attracted attention around the world. However, it is unclear whether the applicability of the elevational Rapoport's Rule differs between organisms from different biogeographical regions. We used Stevens' method, which uses species diversity and the averaged range sizes of all species within each (100 m) elevational band to explore diversity-elevation, range-elevation, and diversity-range relationships. We compared support for the elevational Rapoport's rule between tropical and temperate species of seed plants in Nepal. Neither tropical nor temperate species supported the predictions of the elevational Rapoport's rule along the elevation gradient of 100-6,000 m a.s.l. for any of the studied relationships. However, along the smaller 1,000-5,000 m a.s.l. gradient (4,300 m a.s.l. for range-elevation relationships) which is thought to be less influenced by boundary effects, we observed consistent support for the rule by tropical species, although temperate species did not show consistent support. The degree of support for the elevational Rapoport's rule may not only be influenced by hard boundary effects, but also by the biogeographical affinities of the focal taxa. With ongoing global warming and increasing variability of temperature in high-elevation regions, tropical taxa may shift upward into higher elevations and expand their elevational ranges, causing the loss of temperate taxa diversity. Relevant studies on the elevational Rapoport's rule with regard to biogeographical affinities may be a promising avenue to further our understanding of this rule.

Biogeographical Interpretation of Elevational Patterns of Genus Diversity of Seed Plants in Nepal.

This study tests if the biogeographical affinities of genera are relevant for explaining elevational plant diversity patterns in Nepal. We used simultaneous autoregressive (SAR) models to investigate the explanatory power of several predictors in explaining the diversity-elevation relationships shown in genera with different biogeographical affinities. Delta akaike information criterion (ΔAIC) was used for multi-model inferences and selections. Our results showed that both the total and tropical genus diversity peaked below the mid-point of the elevational gradient, whereas that of temperate genera had a nearly symmetrical, unimodal relationship with elevation. The proportion of temperate genera increased markedly with elevation, while that of tropical genera declined. Compared to tropical genera, temperate genera had wider elevational ranges and were observed at higher elevations. Water-related variables, rather than mid-domain effects (MDE), were the most significant predictors of elevational patterns of tropical genus diversity. The temperate genus diversity was influenced by energy availability, but only in quadratic terms of the models. Though climatic factors and mid-domain effects jointly explained most of the variation in the diversity of temperate genera with elevation, the former played stronger roles. Total genus diversity was most strongly influenced by climate and the floristic overlap of tropical and temperate floras, while the influences of mid-domain effects were relatively weak. The influences of water-related and energy-related variables may vary with biogeographical affinities. The elevational patterns may be most closely related to climatic factors, while MDE may somewhat modify the patterns. Caution is needed when investigating the causal factors underlying diversity patterns for large taxonomic groups composed of taxa of different biogeographical affinities. Right-skewed diversity-elevation patterns may be produced by the differential response of taxa with varying biogeographical affinities to climatic factors and MDE.

[Study on the epidemiological significance related to community-structural difference of the rat plague host and vectors in Western Yunnan, China].

OBJECTIVE: To study the epidemiological significance of community-structural difference regarding both small mammal and flea communities on Rattus flavipectus in Dehong and Baoshan areas, Yunnan province, during 1982 to 1996. METHODS: Methodologies as cluster analysis, communities dominated constitution and species diversity were used for data analysis. RESULTS: 75 490 small mammals of 27 species could be divided into three types: I. Ruili habitat-communities dominated by R. flavipectus (54.41%) and Suncus murinus (33.37%); II. Longchuan and Yingjiang habitat-communities dominated by R. flavipectus (62.99%), S. murinus (23.25%) and Mus musculus (10.06%); III. Baoshan habitat-community dominated by R. flavipectus (48.07%), S. murinus (19.56%) and Crocidura attenuats (14.37%). The captured 61 122 fleas of 11 species on R. flavipectus could be divided into three types: i. Ruili habitat-communities dominated by Xenopsylla cheopis (83.51%) and Lentistivslius ferinus (13.86%); ii. Longchuan and Yingjiang habitats X. cheopis (74.42%) and L. segnis (22.94%); iii. Baoshan habitat-communities dominated by L. segnis (70.62%) and X. cheopis (22.70%). There had been 1471 strains of Y. pestis isolated from the hosts of 7 species and vectors of 5 species in Dehong areas for the ten year period. 36 strains of Y. pestis were isolated from host of one species and vectors of 2 species in Baoshan area for ten years. The constitution ratio of R. flavipectus and X. cheopis was higher in Dehong area with average as 58.70% and 78.97% respectively. However, the diversities of species among host and vector communities were low, with average as 1.010 and 0.625. On the contrary, the constitution ratios of R. flavipectus and X. cheopis were lower in Baoshan area, with an average as 48.07% and 22.70% respectively but the diversities of species among host and vector community were higher with the averages as 1.471 and 0.829 respectively. The main dominative flea species from 'group ii' to 'group iii' in the flea community had changed from X. cheopis to L. segnis. CONCLUSION: The species diversity index of host and vector community was higher in Baoshan area, while the constitution ratio of main host and vector community was lower. This findings seemed to be the important factor of the decrease of plague prevalence in Baoshan area.